Since he first stepped into the limelight a decade ago, Ricky Gervais has become adept at dealing with criticism.

"The first reviews for The Office were awful," he says of the mockumentary which made his name in 2001. "They used the phrase 'summer stinker' I seem to remember."

Although his brand of humour may be of the Marmite variety, his star has since risen to a stratospheric level. He has a trophy cabinet full of Baftas, is renowned on both sides of the Atlantic and has presented the Golden Globes three times.

But he still lands himself in hot water every so often.

Take last year, when he referred to Britain's Got Talent finalist Susan Boyle as a 'mong' in a stand-up gig, sparking complaints from hundreds of angry viewers and Down's Syndrome groups who said the word was still associated with the condition.

"That's gone into myth and legend, but I said at the time, I'd never use that word to mean Down's Syndrome, never would, never have," he says today.

It's not surprising, then, that Gervais is expecting a negative reaction to his latest mockumentary, Derek, which has a one-off showing on Channel 4 this month.

Set in an old people's home, it follows the lives of those who live and work there, with the camera guided by Gervais as Derek, a care assistant who outwardly appears to have learning difficulties.

"I would be confused if no one attacked me about this," he says. "Every week has been the end of my career for the last 20 years. I mean, I started with a backlash. But what can you do? If you started making it for reviews or awards, or the public, you'd never get anywhere. I make it for me."

Gervais denies that Derek is disabled. "He's not that bright, but he's cleverer than Baldrick. He hasn't got as big a problem as Mr effing Bean.

"I've never thought of him as disabled. When I portray a disabled person, I get the person with that disability to play them, so the wheelchair-bound woman in The Office was an actress who uses a wheelchair and there was a guy with Down's Syndrome in Extras."

Derek is perhaps Gervais's most touching character yet. Yes, he believes the 'documentary' he's being filmed for is actually an episode of Secret Millionaire, and yes he talks in a slow way with his mouth gaping, but he's very kind and honest.

"I think it's time to have an antidote to fame, I just want to do normal people again," says Gervais, who turned 50 last summer.

"People assume my work is always meant to be outrageous and cynical but it's never been. There were always happy endings in The Office and Extras. So this is all about kindness and forgotten people on the periphery of society."

The programme co-stars Gervais's best friend Karl Pilkington in his first acting role as the old people's home's slightly dour caretaker Dougie, and comic Kerry Godliman as care worker Hannah.

He says that like all good sitcoms it's a family, with Hannah as the mum, Dougie as the dad and everyone else as the children.

"The difference between this and other sitcoms I've done is there's no real veil of irony, people are saying exactly what they mean, unlike the talking heads in The Office who said things in juxtaposition to what you actually saw them do."

He also enjoyed playing a character with no real ego. "Derek's just selfless and unpretentious, he's better than us, and I thought an old people's home was the perfect place for him.

"No one cares about old people in this country, it's really weird. It's the arrogance of youth, but you're definitely going to be old. That's the one thing that is definitely going to happen to you," he says, with his trademark chuckle.

Naturally the setting means there's as much scope for sadness as there is for humour, and towards the end of the episode we see Derek in tears.

"It's a comedy drama, but then everything is because that's what life is. You try and have a laugh all the time and then you find a lump and it's how you deal with it. I do like getting close to real emotions," says Gervais.

He had been toying with the character of Derek for 12 years and even wrote him into one of his stand-up routines.

"It was an excuse to see the world differently. He'd be introduced and say things like, 'My mum doesn't know I'm here' and then he'd get everything wrong. He was an excuse to deconstruct everything."

He admits all his work is "semi-autobiographical" and that Derek, along with David Brent and Andy Millman, "has got a lot of me in them".

After frequent collaborations with his writing partner Stephen Merchant, Gervais has gone it alone for Derek, which he hopes will be commissioned for a full series.

"It's lonelier," he admits. "It's fun collaborating, but it's still a compromise. You get around it by shouting so loud they let you have your own way!"

He's also directing and producing the comedy drama, which gives him more control.

"It feels easier to be in amongst it, because I know what I want. Writing and directing is fused because I don't think of lines and then wonder how I'm going to do them, I always imagine it on the telly.

"The only reason I started directing and producing was to protect the sort of writing I did."

He's still amazed that he and Merchant got The Office commissioned. "The script could still be in someone's drawer. 'A bloke who isn't funny says something unfunny, looks at the cameras and touches his tie'. That's comedy gold!" he laughs.

"I remember the first meeting we had for it. I said, 'We're going to write it, I'm going to star in it, there's going to be no stars in it, there's going to be no laughter track and we're going to direct it. You either say yes or we take it somewhere else'.

"After the meeting, Steve went, 'Rick, can I do the talking in future?' And when we got it I said, 'See, Steve?' and he went, 'Yeah, but we could be living in a car!'"

Besides writing a whole series of Derek, Gervais is working on a one-hour special of most recent sitcom Life's Too Short, which will feature Les Dennis and Keith Chegwin, as well as Warwick Davis.

He's got plans for a new tour in America and Europe, and he's teaming up with Clyde Phillips, the producer of Dexter, to write an American show about an atheist who goes to heaven.

"I was going to take a step back from it, but I've got a part and I've bigged my part up. I play God. It's a stretch," he chuckles.

Ricky's characters

- David Brent in The Office (2001-3): The bumbling general manager of the Slough-based paper company was famously deluded, believing himself to be funny and popular.

- Andy Millman in Extras (2005-7): More self-aware then Brent, the aspiring actor was best friends with Maggie, played by Ashley Jensen.

- Mark Bellison in The Invention Of Lying (2009): In an alternate reality, down-on-his-luck Mark tells the world's first lie, which makes him immensely powerful.

- Dr McPhee in Night At The Museum (2006 and 2009): In two instalments of the family-friendly adventure, Gervais played the boss of a museum security guard (Ben Stiller) who realised the exhibits came to life at night.